1. Field of the Invention
The present invention relates to an out-of-liquid sensor mounted in a liquid supply route, and a liquid supply device using the same.
2. Description of the Related Art
Methods commonly used to apply chemical solutions to treatment objects and to treat these objects entail supplying water, warm water, or another diluting solution to a treatment device; gradually supplying a concentrated chemical solution to the supply route; preparing a dilute chemical solution having a predetermined concentration and applying the solution to the treatment object, rater than supplying a diluted solution prepared in advance to the treatment device and applying the solution to the treatment object. There are also methods in which a diluting solution and a concentrated chemical solution are supplied in advance to a chemical solution storage tank, adjusted to a predetermined concentration, and applied to the treatment object, in which case the diluting solution and the concentrated chemical solution are automatically supplied to the chemical solution storage tank when the liquid level in the chemical solution storage tank decreases. With some treatments, it is sometimes the case that solely the chemical solution in the treatment solution is used up and gradually replenished. In such cases, a chemical solution supply device for continuously or intermittently supplying a chemical solution to a predetermined location in the treatment device is provided separately from the treatment device.
Examples of treatment devices provided with such chemical solution supply devices include automatic commercial dishwashers for washing dishes and the like; commercial washers and driers for cleaning clothing, blankets, and the like; treatment devices for dyeing, washing, and otherwise treating fabrics and other textile products; wastewater treatment devices for industrial wastewater and the like; scale inhibitor supply devices for cooling towers and the like; devices for replenishing fertilizer and the like for hydroponics; devices for washing automobiles, aircraft, and the like; devices for washing milking machines and other dairy machinery; devices for washing food products and foodstuffs; various types of washing devices in food processing plants and the like; washing devices for electronic components; washing devices for metalworking components, machines, and the like; and bottle washing devices for alcoholic beverages, drinks, and the like.
In such treatment devices, the chemical solution is usually supplied automatically, and the supply source (bottle or the like) and supply line are integrated with the treatment device, making it more difficult for the operator to frequently check on the remaining amount of the chemical solution, and creating a tendency whereby the system runs out of solution during treatment. In this case, optimal drug concentration is impossible to maintain if the discovery of the out-of-liquid condition is delayed, whereby the treatment becomes inadequate, considerable labor is required for reprocessing, and substantial amounts of water, gas, electricity, and other types of energy are expended to obtain warm water, resulting in low economic efficiency.
Arrangements adopted in view of this situation include those in which the chemical solution supply line is fitted with an out-of-liquid sensor, and a warning is immediately issued if the supply of the chemical solution is disrupted. Examples of such out-of-liquid sensors include pressure sensors in which the pressure inside a piping is commonly kept at a negative level, and the negative pressure is released if the bottle, that is supply source, becomes empty; and photosensors in which the refractive index of light varies depending on the presence of a liquid (see, for example, Patent Reference 1). In addition, it has recently been proposed to use out-of-liquid sensors in which a pair of electrodes is extended into a liquid conduit, and the out-of-liquid condition is accurately detected by directly measuring the electrical conductivity of the liquid (see, for example, Patent Reference 2).
[Patent Reference 1]
Japanese Patent Application Laid-open No. 2000-338115
[Patent Reference 2]
Japanese Patent Application Laid-open No. 2000-170663
However, such pressure sensors are disadvantageous in that they often malfunction and issue a warning when there is no out-of-liquid condition. In addition, most of the photosensors are mounted on the outside of a tube in a liquid supply line and are used to detect the presence or absence of a liquid in the tube. With this type of device, the sensor must be selected in accordance with the tube diameter or the type of liquid, and the sensitivity thereof must be adjusted, bringing about problems in terms of labor and cost.
Meanwhile, out-of-liquid sensors in which the electrical conductivity of liquids is measured directly are disadvantageous in that although no malfunctions occur in the initial period of installation, the electrodes in the sensors must still be periodically replaced because these electrodes come into direct contact with chemical solutions, and therefore become corroded or worn over time, resulting in reduced sensitivity. Another drawback is that these electrodes can be used solely with electrolyte-containing chemical solutions.
An object of the present invention, which was perfected in view of this situation, is to provide a highly universal out-of-liquid sensor that allows an out-of-liquid condition to be accurately detected for a long time, and to provide a liquid supply device using the same.
Provided in order to attain the stated object, the first aspect of the present invention is an out-of-liquid sensor which is mounted in a liquid supply route for supplying a liquid to a predetermined location, and which forms a part of the liquid supply route, comprising a light-transmissive tubular body, the opening at one end of which is formed into a connecting section capable of communicating with an upstream piping of the liquid supply route, and the opening at the other end of which is formed into a connecting section capable of communicating with a downstream piping of the liquid supply route, and in which an internal bore section communicating between the two connecting sections is formed in the liquid-transmitting channel; and also comprising a photosensor mounted on the tubular body; the detector of the photosensor functioning in such a way as to sense, through the light-transmissive wall surface of the tubular body, the presence or absence of a liquid flowing through the internal bore section.
According to the second aspect of the present invention, the out-of-liquid sensor of the first aspect has particular features whereby the photosensor is a transmissive photosensor, and the light-emitting section and light-receiving section thereof are embedded on the opposite sides of the internal bore section of the tubular body.
The third aspect of the present invention is an out-of-liquid sensor which is mounted on the lid of a liquid-filled container prepared as a liquid supply source for supplying a liquid to a predetermined location, and which forms a part of a liquid supply route extending from the liquid supply source, comprising a light-transmissive tubular body, the opening at one end of which is formed into a connecting section capable of communicating with a liquid suction piping for engaging an opening formed in the lid of the liquid-filled container and drawing out the liquid in the container, and the opening at the other end of which is formed into a connecting section capable of communicating with a downstream piping of the liquid supply route, and in which an internal bore section communicating between the two connecting sections is formed in the liquid-transmitting channel; and also comprising a photosensor mounted on the tubular body; wherein the detector of the photosensor functions in such a way as to sense, through the light-transmissive wall surface of the tubular body, whether there is a liquid flowing through the internal bore section.
According to the fourth aspect of the present invention, the out-of-liquid sensor of the third aspect has particular features whereby the photosensor is a transmissive photosensor, and the light-emitting section and light-receiving section thereof are embedded on the opposite sides of the internal bore section of the tubular body.
The fifth aspect of the present invention is a liquid supply device for supplying liquid to a predetermined location, comprising liquid delivery means for drawing a liquid from one end and discharging the liquid at the other end; a liquid suction piping, one end of which is connected to a liquid supply source, and the other end of which is connected to the suction side of the liquid delivery means; and a liquid discharge piping, one end of which is connected to the discharge side of the liquid delivery means, and the other end of which is connected to the predetermined location; wherein the out-of-liquid sensor according to the first aspect or the out-of-liquid sensor according to the second aspect is mounted in the liquid suction route between the liquid supply source and the suction side of the liquid delivery means via the liquid suction piping, or in the liquid discharge route between the discharge side of the liquid delivery means and the predetermined location via the liquid discharge piping; and predetermined warning means is set to be activated when the photosensor in the out-of-liquid sensor detects an absence of liquid in the internal bore section of the tubular body.
The sixth aspect of the present invention is a liquid supply device for supplying liquid to a predetermined location, comprising liquid delivery means for drawing a liquid from one end and discharging the liquid at the other end; a liquid suction piping, one end of which is connected to a liquid-filled container prepared as a liquid supply source, and the other end of which is connected to the suction side of the liquid delivery means; and a liquid discharge piping, one end of which is connected to the discharge side of the liquid delivery means, and the other end of which is connected to the predetermined location; wherein the out-of-liquid sensor according to the third or fourth aspect is mounted on the lid of the liquid-filled container; and predetermined warning means is set to be activated when the photosensor in the out-of-liquid sensor detects an absence of liquid in the internal bore section of the tubular body.